An Organic Light-Emitting Diode (OLED) display is one of hot topics in a current display research field. As compared with a Liquid Crystal Display (LCD), the OLED display has advantages of low energy consumption, low production cost, self-luminescence, a wide viewing angle, a fast response speed, and the like. Currently, in display fields such as mobile phones, tablet computers, and digital cameras, OLED displays have begun to replace traditional LCD displays.
Unlike an LCD display, which controls brightness with stable voltages, the OLED display is current-driven and needs a steady current to control its light emission. Due to manufacture processes, device aging, and so on, threshold voltages Vth of driving transistors that drive the OLED display to emit light may be uneven, resulting in a change in a current flowing through each OLED to cause uneven display brightness, and then a display effect of an entire image is affected. Moreover, since the current flowing through each OLED is related to a power supply voltage connected with a source electrode of the driving transistor, IR drop may also cause current difference in different regions, which further causes uneven brightness of the OLED display in different regions.